The present invention relates to an aircraft power distribution system, and more particularly to an aircraft power distribution system that combines an alternating current power panel and a high voltage direct current motor controller panel which minimizes power loss from feeder resistance while maximizing weight savings.
Conventional gas turbine powered aircraft provide a variety of power to the aircraft in addition to the thrust required for propulsion. The three main power draws from the engine are electrical, bleed air, and pneumatic/hydraulic. In addition to the engine driven generators that provide electrical power to the aircraft, bleed air is drawn off the engine and used for the aircraft pressurization, cooling and heating systems. The pneumatic/hydraulic systems are pressurized with pumps which are driven by an engine driven gearbox. Each of these conventional power distributions systems reduces the engine efficiency and the resulting thrust for aircraft propulsion.
Conventional electric power generation and distribution systems for commercial aircraft typically include a generator located on and driven by each of the aircraft's engines which have a rating anywhere from 80 kVA to 300 kVA. The power produced by the engine mounted generators is routed into the aircraft to what is commonly referred to as primary distribution panels. This power is traditionally 3 Phase, 115 VAC, 400 hz.
Conventional power distribution systems route the electric power to a single electronics bay in the front of the aircraft that is generally below the cockpit. The primary distribution panels are segregated on the right and left side of the aircraft and the power from the primary panels is routed to secondary distribution panels usually, located in the cockpit. The secondary distribution panels transfer power to the required loads such as to power electric motors, lights and other aircraft systems. In between the primary and secondary panels, the power may be converted to DC to provide for many of the direct current loads required in the cockpit such as avionic systems.
Such conventional power distribution systems are effective for current generation aircraft as such aircraft utilize the extensive bleed air, pneumatic, and hydraulic power distribution systems which minimizes electrical power distribution system requirements.
Recently, aircraft systems are tending toward a greater usage of electrically powered equipment which eliminate the bleed air system and minimizes the pneumatic and hydraulic systems. These “more electric” aircraft power distribution systems operate at significantly increased power levels on the order of 1,000 kVA. Conditioning systems such as cabin pressure, cooling and heating are powered by electric motors. The hydraulic pumps are also driven by electric motors. In addition, without a bleed air system to spin-up the engine during start, the generator operates as a motor during the start sequence to spin up the turbine.
All these relatively large electric motors, used to power pumps and compressors, require motor controllers that provide the appropriate current and voltage per torque requirements. This is achieved by providing DC power to motor controllers that invert the power to AC and drive the electric motors. Furthermore, because the power requirements are relatively large, the voltage of the “more electric” aircraft power system has all been increased to reduce operating current. Current requirements drive wire size, weight and route flexibility throughout the aircraft.
A difficulty of the “more electric” aircraft power system resides in the amount of power being moved. To transfer the relatively greater power requires larger cable or may require multiple cables that share the current to permit proper routing throughout the aircraft structure. Each time a cable leaves a panel on an aircraft and is routed to a different panel, the cable is protected against failure modes, which requires further protective systems such as current transformers that sense a short and command a controller to open a relay. Protective systems increase aircraft weight and are necessary, but directly affect performance in terms of range, fuel burn and operation cost.
Accordingly, it is desirable to provide an aircraft power distribution system which produces significant weight and power loss reduction while handling increased electrical loads expected of “more electric” aircraft power systems.